Dimetropus osageorum n. isp. from the Early Permian of Oklahoma (USA): A Trace and its Trackmaker

摘要

A new ichnospecies is named as Dimetropus osageorum n. isp. within the ichnogenus Dimetropus Romer and Price, 1940. The new ichnotaxon comes from the Lower Permian Midco Member of the Wellington Formation, cropping out near Perry, Noble Co. (Oklahoma, USA), and differs from congeneric ichnospecies in the apparent heteropody and in the proportionally shorter digits. The characters of the new ichnotaxon, together with comparative analysis of footprints and of known skeletal remains, suggest referral of the trackmaker to the Caseidae, although edaphosaurid affinities cannot be excluded. Tracks referred to Dimetropus exhibit wide variation, and their respective trackmakers may be ascribed to an accordingly wide range of different zoological taxa among non-therapsid Synapsida and not only to Sphenacodontidae as has been generally believed. At the same time, the process of attributing ichnotaxa, on the basis of well preserved tracks and by comparison with known skeletal remains, is validated.